1. www.soran.edu.iq Ecology M. Saadatian Geochemical cycle 1

2. www.soran.edu.iq Geochemical cycle water cycle nitrogen cycle phosphorus cycle carbon cycle

3. www.soran.edu.iq Water Cycle Water Cycle - the continuous process by which water moves from bodies of water, land and living things on earth's surface to the atmosphere and back to Earth's surface ♦ Evaporation - process by which the surface of a liquid absorbs enough energy to change into a gas ♦ Transpiration - process by which water is evaporated through a plant's leaves ♦ Condensation - process by which a gas changes to a liquid ♦ Precipitation - different forms of water that falls back to the Earth's surface ♦ can be rain, sleet, hail, or snow depending on temperature

4. www.soran.edu.iq The Nitrogen Cycle direct Nitrogen Fixation- Special bacteria convert the Nitrogen gas (N2) to ammonia (NH3) which the plants can use (azetobacter, Clostridium). Mineralisation Step 1- Ammonification- After all of the living organisms have used the nitrogen, decomposer bacteria convert the nitrogen-rich waste compounds into simpler ones like ammonium NH 4+ (micrococcus). Step 2- Nitrification- Nitrification is the process which converts the ammonium into nitrite (NO2-) and nitrate (NO3-) ions which the plants can take in as nutrients (Nitrosomonas, nitrobacter).Nitrosomonas Step 3- Denitrification- Denitrification is the final step in which other bacteria convert the simple nitrogen compounds back into nitrogen gas (N2), which is then released back into the atmosphere to begin the cycle again ( Pseudomonas).

5. www.soran.edu.iq The Phosphorus Cycle

6. www.soran.edu.iq Carbon Cycle The movement of carbon, in its many forms, between the atmosphere, hydrosphere, biosphere, pedosphere and lithosphere is described by the carbon cycle. The same carbon atoms in your body today have been used in countless other molecules since time began. The wood burned just a few decades ago could have produced carbon dioxide which through photosynthesis became part of a plant. When you eat fruit and vegetables, the same carbon from the wood, which was burnt, can become part of you

7. www.soran.edu.iq Carbon cycle: 1.The Geological Carbon Cycle 2. The Biological Carbon Cycle

8. www.soran.edu.iq The Geological Carbon Cycle Geological forces have slowly produced carbonic acid, (a weak acid formed by the reactions between atmospheric CO2 and water): CO2 + H2O H2CO3 carbonic acid will break down to produce water and CO2. This oscillating reaction continues until a chemical equilibrium is achieved. H2CO3 H+ + HCO3- fix bicarbonate with calcium (Ca2+) to produce calcium carbonate (CaCO3). This substance is used to produce shells and other body parts by organisms such as coral, crustaceans, some protozoa, and some algae.

9. www.soran.edu.iq The Biological Carbon Cycle through the processes of photosynthesis and respiration. Through photosynthesis, green plants use solar energy and water to turn atmospheric CO2 into carbohydrates (i.e. sugars, starch and cellulose): energy (sunlight) + 6CO2 + H2O ---> C6H12O6 + 6O2 When oxygen is present, aerobic respiration occurs, which releases carbon dioxide into the surrounding air or water, following the reaction C6H12O6 (organic matter) + 6O2 ---> 6H2O + 6CO2 + energy When oxygen is lacking, for example, in soil that is stagnant due to poor drainage then the breakdown of carbon compounds is carried out by microbial communities that catalyze the breakdown of organic matter without oxygen (anaerobically) to produce methane and carbon dioxide following the equation below: C6H12O6 --->3CH4 + 3CO2

10. www.soran.edu.iq